Tigerloop™ Article

Tigerloop™ Article - As seen in Fuel Oil News Magazine

by Lindy Lindtveit

“Why, that
looks just like R2D2 from Star Wars!”

That’s the typical reaction you hear from a burner tech that
sees the new Tigerloop oil de-aerator for the first time. And
while it’s not exactly a duplicate of that little robot (see
picture), it does look quite different from the former Tigerloop.
The new Model TN, introduced in early 2005 by Westwood Products,
the US importer of Tigerloop, replaces the Model T60I, which,
since its debut more than twenty-five years ago, has become the
standard by which all oil de-aerators are judged worldwide. And
while it might be said: “when you have a winner, stick with
it...” the makers of Tigerloop saw the natural evolution of the
product as meeting the challenges for better performance and the
industry-wide emphasis on more environmentally friendly oil heat
systems. Hence the new Model TN, an environmentally friendly
package boasting 33% greater de-aeration capacity, dual chamber
design for added safety, and easier mounting and installation.
And like the former Tigerloop, the new Model TN is the only UL
approved oil de-aerator available. Truly, oil de-aeration has
reached a new level.

De-Aeration

But to fully
appreciate the new Model TN Tigerloop and what it does, let’s
get technical for a moment. What is an “oil de-aerator”, and
what does it do? Simple put, an oil de-aerator removes the air,
or more precisely the bubbles, from the fuel so that
these bubbles don’t cause all kinds of mischief in the fuel
system. Bubbles cause mischief? How can those soft little
things that make bubble baths, champagne, and exotic dancers so
much fun cause mischief? Well, in a fuel system they can.
Remember, safe, reliable oil heat needs basically two things:
(1) good equipment that is well maintained, and (2) clean fuel
that is free of contamination. And by contamination we mean no
dirt, water, or bubbles. So, let’s look at why, “Bubbles
are Bad”.

“Bubbles are
Bad...”

We find two
kinds of bad bubbles in fuel systems: air and gases. If it’s
air bubbles, it means either a leak in the system or the bubbles
were delivered with the oil. Leaks can be fixed if they can be
found. Delivered air is another story. These bubbles are
suspended in the oil when it arrives and is the result of the
oil having been churned up during loading, transporting, and
delivery. Take and fill an empty soft drink bottle with fuel
oil and give it a shake to simulate the kind of treatment that
fuel oil gets between the loading rack and its ultimate
destination in the customer’s tank. You’ll see how long it
takes to clear, and that’s just the bubbles you can see with the
naked eye. The really small bubbles you can’t see, and those
are the ones that can accumulate in even the tightest of
systems. No job is immune; all systems have these bad
bubbles.

So, what do these air bubbles do that makes them so bad? Take a
look at Diagram 1.

Diagram 1.

It’s a cut-away diagram of a pump operating normally, except for
the air bubble lodged in the nozzle line (see arrow). The
bubble is deceivingly small, since its size has been compressed
by the 100 psi pressure in the nozzle line. As long as the pump
operates, the bubble will remain small and compressed, having no
effect on burner operation.

But when the pump shuts down it’s a different story. As the
pump’s rpm decreases, the piston will close against the nozzle
seat cutting off the flow of oil from the pump, but not the
flow of oil from the nozzle. The expanding bubble has taken
over for the pump in supplying the pressure pushing oil out the
nozzle (Diagram 2.).

Diagram 2.

Oil flow
does not cease until the bubble has expanded back to its
original size and nozzle line pressure has dropped to zero
(Diagram 3.).

Diagram 3.

The result
is virtually no cut-off, with a sooty, smoky shutdown. Ever
heard of “nozzle coking”? It’s a popular phrase nowadays. And
a solenoid valve won’t help this problem. It’s strictly a
bubble thing. But there’s more...

Glance over at Diagram 4.

Diagram 4.

It’s a
cut-away of a pump’s strainer chamber, with the pump operating
normally. Note that the level of the oil does not fill the
entire strainer chamber. This is normal because during bleeding
the oil level only rises high enough to just cover the inlet to
the gear set, about 2/3 of the way up the strainer chamber. But
that’s not bad because the air cushion at the top quiets the
hydraulic whine of the gear set and doesn’t affect pump
operation. As long as the inlet to the gear set stays covered,
all is well.

But, if air enters the pump it will immediately rise to the top
pushing down the oil level in the strainer chamber and partially
uncovering the inlet to the gear set (Diagram 5.).

Diagram 5.

The gear set
starts gulping air and oil and the pressure becomes unstable
resulting in poor combustion, noise, rumbling, pulsation, etc.
If enough air enters, the oil level drops completely below the
inlet to the gear set (Diagram 6). Pressure is lost and
the burner eventually locks-out.

Diagram 6.

The second kind of bad bubbles are gases. These come from
dissolved vapors and volatiles that are drawn out of the oil
when it’s exposed to vacuum. The higher the vacuum the more
bubbles produced. Such things as high lift, long runs,
undersized tubing, restricted lines, partially plugged filters,
and sticky check valves are all major causes of high vacuum that
can literally boil volatiles out of the oil creating bubbles.
Diagram 7. shows the familiar story.

Diagram 7.

The bubbles
drawn out of the oil rise to the top of the strainer chamber,
the oil level falls, the gear set gulps foamy oil, pressure
becomes unstable, and the burner eventually locks-out.

Certainly, safely handling the problem of bad bubbles is a major
feature of the new Tigerloop. But, it’s more than just a bad
bubbles problem solver. All systems benefit from the use of a
Tigerloop, as you will see when we continue exploring the new
Tigerloop and its application and installation next time. (in
Part 2)

PART 2

In Part 2.
we pick up our discussion of the new Tigerloop Model TN oil
de-aerator introduced in early 2005 by Tigerholm of Sweden and
Westwood Products of the US. The new Model TN replaces the
former Model T60I, which is the original oil de-aerator and
which is installed on millions of jobs worldwide. Boasting
higher de-aeration capacity, better performance, easier
installation, and some environmentally friendly features, the
new Model TN is sure to maintain Tigerloop’s 25 year long
leadership position in the field. And, like its predecessor,
the new Model TN is UL listed, which makes it the only UL
approved oil de-aerator available in the US.

Last time we learned that “Bubbles are Bad” and discussed the
two kinds of bad bubbles: Air and gasses. Both cause after
drip and nozzle/combustion head coking problems, as well as
burner lockouts, by pushing the oil level in the strainer
chamber of the pump down below the inlet to the gear set. And
whether bubbles enter the system via a leak, or are drawn out of
the oil due to high vacuum makes no difference, they still have
the same detrimental affect on the system. Therefore, to
eliminate the problems you must eliminate the bubbles.

One-Pipe vs.
Two-Pipe

Unfortunately, there is no piping arrangement that can, by
itself, eliminate the bubbles. One-pipe systems are simple, use
less material, prolong filter life by only passing the oil
through the filter once, and pre-heat the oil because it moves
through the piping slowly. But, they can’t deal with those bad
bubbles, either air or gases. Two-pipe systems can be used on
higher lift jobs because they can deal with some of the bubble
problems caused by higher vacuum, but they are harder to
install, use more material, load up filters much faster, and
constantly bring in cold oil to the pump. Moreover, the return
line is a pressurized oil line that can be an environmental
nightmare if it should develop a leak.

The Best of
Both Worlds

What
Tigerloop does is combine all the safety and simplicity of the
one-pipe system with the added performance of the two-pipe
system (Diagram 8.).

Diagram 8.

From the
tank to the Tigerloop it’s one-pipe, with no return line that
can leak into the ground. The only oil moving up that inlet
line is what’s going out the nozzle so filters last longer and
the oil has time to pre-heat to ambient temperature before
reaching the pump. Between the Tigerloop and the pump it’s
two-pipe, with all the self-priming, bubble handling, high lift
capabilities of a two-pipe system. Long, high lift jobs are
possible because (1.) flow rate from the tank is low so vacuum
is lower, and (2.) any bubbles (foam) developed due to vacuum
are handled by the Tigerloop. So, while bubbles may be bad,
they’re not a problem.

Installation

IMPORTANT NOTE:

WARNING: INSTALLATION MUST BE
PERFORMED BY A QUALIFIED TECHNICIAN FAMILIAR WITH OIL HEATING
SYSTEMS, EQUIPPED WITH THE PROPER TOOLS AND EQUIPMENT, FAMILIAR
WITH ALL GOVERNING CODES AND ORDINANCES, AND LICENSED BY THE
PROPER AUTHORITY WHERE APPLICABLE. INSTALLATION BY AN
UNQUALIFIED PERSON CAN RESULT IN HAZARDS TO THAT PERSON AND
OTHERS. THESE HAZARDS MAY INCLUDE SPILLAGE OF FUEL OIL, FIRE,
SEVERE BURNS, DAMAGE TO SYSTEM COMPONENTS, AND OTHER HAZARDS.

The following
installation instructions are not complete. Complete
Installation Instructions are packaged with the Tigerloop.

Installation
of the new Model TN is even easier than the former model. It
has a new detachable mounting bracket that allows the bracket to
be mounted first and then the Tigerloop snapped into position.
The Tigerloop should be vertically plumb, that is, mounted
upright with the vent on top, inlet port on the bottom. That's
important because there are floats inside that must be free to
move up and down.

The fusible valve that comes packaged with the Tigerloop should
be installed directly into the inlet port on the bottom. If the
tank is above the Tigerloop, an oil line safety valve is
recommended. A good line filter is a must on all jobs and
should be installed between the tank and the Tigerloop. Do not
install a filter, or anything else that could cause a
restriction (i.e. a valve), in either line between the Tigerloop
and the pump. This is very important, as any restriction in
these lines may cause the pump seal to leak.

Each Tigerloop can handle one burner firing up to 20 GPH. If
the burner fires more than 20 GPH, two or more Tigerloops can be
connected in parallel to supply the required nozzle capacity.
On jobs with more than one burner, a single oil line can be used
to supply all the burners by using one Tigerloop for each
burner. The Tigerloops are "teed" into the one line coming from
the tank and the normal supply and return lines are run between
each individual Tigerloop and it's corresponding burner. Just
remember, each burner requires its own Tigerloop - no sharing
Tigerloops!

The actual piping of the Tigerloop is straight forward and quite
easy. Diagram 9. shows a simple one-pipe system, gravity fed, a
great candidate for a Tigerloop.

Diagram 9.

The first
step is to mount the Tigerloop in a convenient place close to
the burner. Flexible oil lines, available in 24" or 36"
lengths, make the piping easy between the Tigerloop and the pump
and are a real asset on swing-out door boilers. It's easiest to
install the fusible valve and the fittings in the Tigerloop
before snapping it into the wall bracket. Once mounted,
attaching the inlet line from the tank and the flexible lines to
the pump are easy. Just remember to install the by-pass plug in
the pump before connecting the lines! When using a Tigerloop,
the pump must always be set for two-pipe or the system will not
work. Diagram 10. shows the completed piping. The former
one-pipe system is now a Tigerloop system.

Diagram 10.

Diagram 11.
shows a simple two-pipe system.

Diagram 11.

It can be
converted to a Tigerloop system using the same basic steps
outlined above for the one-pipe system. This time, however, you
can ignore the step about installing the by-pass plug because
it's already installed. Just make sure that the old return line
that will no longer be used is capped off (sealed) leak tight.
It would be a shame to have the next oil delivery's fast fill
push oil up and out the old return line creating an
"environmental incident". Diagram 12. shows the completed
piping of the former two-pipe system.

Diagram 12.

Perfecting
the art...

We have all
seen great advances in oil heating equipment in the years since
the height of the "energy crisis". Today's burners are clean
and efficient, and with the modern boiler or furnace make for
unprecedented comfort and economy. But the technology of oil
heating is still developing, and the new Tigerloop TN is part of
that progress. It is truly another step in perfecting the art!